The present invention relates to phased array antennas, and more particularly to an integrated printed wiring board antenna for forming a phased array antenna system in which the antenna elements and their associated electronics are integrated onto one, or a pair of, printed wiring board assemblies.
The assignee of the present application, The Boeing Company, is a leading innovator in the design of high performance, low cost, compact phased array antenna modules. The Boeing antenna module shown in FIGS. 1a-1c have been used in many military and commercial phased array antennas from X-band to Q-band. These modules are described in U.S. Pat. No. 5,886,671 to Riemer et al and U.S. Pat. No. 5,276,455 to Fitzsimmons et al, both being hereby incorporated by reference.
The in-line first generation module was used in a brick-style phased-array architecture at K-band and Q-band frequencies. This approach is shown in FIG. 1a. This approach requires some complexity for DC power, logic and RF distribution but it provides ample room for electronics. As Boeing phased array antenna module technology has matured, many efforts made in the development of module technology resulted in reduced parts count, reduced complexity and reduced cost of several key components of such modules. Boeing has also enhanced the performance of the phased array antenna with multiple beams, wider instantaneous bandwidths and greater polarization flexibility.
The second generation module, shown in FIG. 1b, represented a significant improvement over the in-line module of FIG. 1a in terms of performance, complexity and cost. It is sometimes referred to as the xe2x80x9ccan and springxe2x80x9d design. This design can provide dual orthogonal polarization in an even more compact, lower-profile package than the in-line module of FIG. 1a. The can-and-spring module forms the basis for several dual simultaneous beam phased arrays used in tile-type antenna architectures from X-band to K-band. The can and spring module was later improved even further through the use of chemical etching, metal forming and injection molding technology. The third generation module developed by the assignee, shown in FIG. 1c, provides an even lower-cost production design adapted for use in a dual polarization receive phased array antenna.
Each of the phased-array antenna module architectures shown in FIGS. 1a-1c require multiple module components and interconnects. In each module, a relatively large plurality of vertical interconnects such as buttons and springs are used to provide DC and RF connectivity between the distribution printed wiring board (PWB), ceramic chip carrier and antenna probes.
A further step directed to reduce the parts count and assembly complexity of the antenna module as described above is described in pending U.S. patent application Ser. No. 09/915,836, xe2x80x9cAntenna Integrated Ceramic Chip Carrier For A Phased Array Antennaxe2x80x9d. This application involves forming an antenna integrated ceramic chip carrier (AICC) module which combines the antenna probe (or probes) of the phased array module with the ceramic chip carrier that contains the module electronics into a single integrated ceramic component. The AICC module eliminates vertical interconnects between the ceramic chip carrier and antenna probes and takes advantage of the fine line accuracy and repeatability of multi-layer, co-fired ceramic technology. This metallization accuracy, multi-layer registration produces a more repeatable, stable design over process variations. The use of mature ceramic technology also provides enhanced flexibility, layout and signal routing through the availability of stacked, blind and buried vias between internal layers, with no fundamental limit to the layer count in the ceramic stack-up of the module. The resulting AICC module has fewer independent components for assembly, improved dimensional precision and increased reliability.
In spite of the foregoing improvements in antenna module design, there is still a need to further combine more functions of a phased array antenna into a single component. This would further reduce the parts count, improve alignment and mechanical tolerances during manufacturing and assembly, improve electrical performance, and reduce assembly time and processes to ultimately reduce phased array antenna system costs. More specifically, it would be highly desirable to eliminate dielectric xe2x80x9cpucksxe2x80x9d that need to be used in a completed antenna module, as well as to entirely eliminate the use of buttons, button holders, flex members, cans, sleeves, elastomers and springs. If all of these independent parts could be eliminated, then the only issue bearing on the cost of the antenna assembly would be the material and process cost of manufacturing the antenna assembly.
The present invention is directed to a phased array antenna system which incorporates an antenna integrated printed wiring board (AIPWB) assembly. The AIPWB includes circuitry for DC/logic and RF power distribution as well as the antenna probes. The metal honeycomb waveguide plate used with previous designs of phased array antenna modules is eliminated in favor of a multi-layer printed wiring board which includes vias which form circular waveguides and a plurality of layers (stack-up) for providing a honeycomb waveguide structure and wide angle impedance matching network (WAIM). Thus, the antenna system of the present invention completely eliminates the need for dielectric pucks, which previous designs of phased array antenna modules have heretofore required. The entire phased array antenna system is thus formed from either a single, multi-layer printed wiring board, or two multi-layer printed wiring boards placed adjacent to one another. This construction significantly reduces the independent number of component parts required to produce a phased array antenna system. Each of the two printed wiring boards are produced using an inexpensive, photolithographic process. Forming the entire antenna system essentially into one or two printed wiring boards significantly eases the assembly of the phased array antenna system, as well as significantly reducing its manufacturing cost.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.